In the evolution of modern electronic manufacturing art the long established trend has been toward smaller components and more dense packaging made possible by these components and development of sophisticated circuitizing techniques employing laser technology and the like. Yet an additional trend in order to continue favorable improvements in manufacturing cost reductions has been away from hand work and toward increasingly sophisticated automated assembly techniques. Representative of this are automatic component placement machines such as those depicted in U.S. Pat. No. 4,135,630 and machines such as those manufactured by the Dynapert Corporation Universal Instruments Company, and Panasonic. These machines employ robotics-type techniques to automatically place various pin-in-hole surface mount or other components, on substrates or circuit boards as desired.
Whereas the current state of the art with respect to such automated placement devices is predominantly of the type wherein single components are place sequentially, effort is currently being made to advance the art further by means of machines capable of placing a plurality of components simultaneously. One example of such a machine is provided by Panasonic National, details of a representative system thereof being set forth in a publication entitled "Specifications: Panasert Simultaneous Chip Component Placement Machine Model No. NM-8270". As the art continues to develop, tremendous manufacturing throughput capability thereby results wherein it becomes possible to place large numbers of components on boards at extremely rapid rates.
One very serious problem with such tremendous throughput is in feeding components to the machines for automated placement in a form which may readily be used by the particular machine. One technique for attempting to solve the problem has been to place the components on a tape for tape feeding. However with the advent of simultaneous component placement equipment and the increasingly smaller dimensions of the various components, techniques such as those disclosed in the aforementioned Panasonic machine are beginning to be employed wherein components are loaded or stacked vertically in carrier tubes for use by the machines.
Notwithstanding improved packaging techniques for storing components and delivering them to the machines such as the tubes just mentioned, a serious problem remains in how to package such components in tubes in a rapid, economical and yet reliable fashion. The urgent need for a quick and efficient means to effect such packaging may be understood when it is considered that with the increasing costs of such sophisticated placement machinery, down time while awaiting a supply of appropriately configured chips is prohibitively expensive and unacceptable.
However, lack of available equipment for quickly, economically and reliably loading tubes with increasingly smaller and smaller components has seriously impeded progress toward adoption of simultaneous placement and other techniques for substantially improving manufacturing throughput. Numerous difficult problems are associated with providing such tube loading machinery which are not readily apparent. First, due to the extremely minute size of such components placing hundreds of such minute components in a tube in a uniform orientation is non-trivial. With respect to the components themselves, for example, the industry has been plagued with inability to consistently align such small components repeatedly due to innumerable factors including the tendency of components to stick together, and chip dimensional variations arising from non-uniformity in manufacture, broken components, and the like.
Reliably and consistency in placing a vast, uniform number of such minute components in exactly the same orientation within tubes and insuring the integrity of each such component is extremely important. This may be appreciated when it is considered that with the incredible throughput provided by simultaneous placement machines, numerous boards could be populated with chips which were defective or disoriented long before the error was detected in a manufacturing line. This results in extremely expensive waste material or rework cost. Such errors could be caused not only by broken chips loaded into the tubes, but even in some instances by inverted chips having contact pads on only one side which must be consistently loaded with these pads oriented in the same way.
Yet another example of the need for 100% accuracy in tube loading is that with dissimilar numbers of components in the various tubes used on a placement machine, numerous boards could be populated with missing components due to tubes having a substandard number of such components running out of chips prior to the other tubes.
One attempt to provide an automated chip loading machine employs a vibratory bowl technique used in the handling of small parts such as screws or the like. In operation this machine provides a helical path down which chips are vibrated from a reservoir until they are somewhat uniformly aligned for subsequent placement in a tube. Numerous drawbacks to such an approach result in the industry still being in need of an effective solution to the component tube filling problem. One serious and immediately apparent drawback is that the machine is adapted to only load single tubes at a time. A large number of such expensive machines is thereby necessitated to hope to even attempt to keep up with the vastly increasing throughput of simultaneous component placement machines as aforesaid. Yet additional serious drawbacks of this machine include lack of visibility of the loading process, difficulty in purging the machine and changeover to begin loading a different component, and failure to provide for detection of dimensional or functional irregularities in the chips.
With the foregoing in mind, it is apparent that a component tube loading machine was desperately needed in the industry which could provide for the consistent loading of various components in tubes wherein the machine was extremely reliable and, had a substantial throughput to enable the tube filling task to keep pace with the throughput of placement machines. Such a machine was also urgently needed which could provide for the loading of a plurality of tubes simultaneously, and which further provided for ease of purging when it was desired to fill tubes with a different component. Still further a component loader was sought which provided ease of visibility of the progress of the components during the loading process, and which further prevented loading tubes with non-uniform components. Yet further features desirable in such a machine were the ability to rapidly change over so as to begin filling another set of tubes and to further do so with a completely different component. These and other desirable features are provided by the subject invention which overcomes the hereinbefore described problems of the prior art.
One problem with the aforementioned carrier tube loading machine disclosed in the aforementioned U.S. patent application Ser. No. 07/347,691, now U.S. Pat. No. 4,974,390, is related to the nature of many of the chips employed in modern electronic circuits. Many of these chips, predominantly of the passive component variety, are provided in the form of a minute rectangular shape having solder lands disposed at opposing ends thereof. However, these solder lands may only appear on one face of the component. Accordingly, it is essential that a mechanism be provided for loading such components into tubes in a consistent orientation with the solder land faces of all such chips in the tube being oriented in the same direction. The reason for this relates to the operation of modern chip placement machines employing these tubes of components. The placement machines will take the chips from the tubes and dispose them with the solder lands facing downward so as to cause the solder lands of the chips to matingly engage corresponding solder lands or pads on the receiving substrate, mother board or the like. Inasmuch as the placement apparatus typically is not provided with means for sensing the orientation of chips as they are expelled from the tube, it is essential that all such components be oriented consistently within the tube. However, due to the extremely minute dimensions of such chips it is extremely difficult to provide for a reliable and inexpensive system and method for consistently orienting such chips in carrier tubes.
This problem is further compounded by the extremely rapid throughput being achieved by modern simultaneous component placement machines which are capable of placing such components at rates in excess of 200-300 components per minute. It may thus be seen that to properly utilize this throughput capacity of the placement machines themselves, it was imperative to devise a tube stuffing machine which could keep up with this throughput in providing magazines or carrier tubes of such chips which were properly oriented.
The present invention has solved this troublesome problem in providing for a reliable, simple and inexpensive means for establishing proper orientation of chips prior to loading in carrier tubes, such invention being further described in greater detail herein and with reference to the accompanying drawings.